The present invention relates to image guided interventional medical procedures. It finds particular application in conjunction with computed tomography (CT) imaging systems and robot assisted needle biopsies, and will be described with particular reference thereto. However, it is to be appreciated that the present invention is also amenable to other like applications using different imaging modalities and/or for different medical procedures.
It is often desired that interventional medical procedures be as minimally invasive as possible. However, it is also desirable to be able to visualize or otherwise know the relative positions and/or orientations of surgical tools or devices with respect to surrounding anatomy. The latter goal may be achieved by a direct inspection of the anatomy. However, in the case of interior anatomy, direct inspection may be more invasive than desired insomuch as additional or larger incisions may have to be made to expose or access the interior anatomy for direct inspection.
For example, it is often desirable to sample or test a portion of tissue from human or animal subjects, particularly in the diagnosis and treatment of potentially cancerous tumors, pre-malignant conditions, and other diseases or disorders. Typically, in the case of tumors, when the physician suspects that cancer or an otherwise diseased condition exists, a biopsy is performed to determine if in fact cells from the tumor are cancerous or otherwise diseased. Many biopsies, such as percutaneous biopsies, are performed with a needle-like instrument used to collect the cells for analysis.
In recent years, the performance of interventional medical procedures such as needle biopsies has been enhanced by the use of x-ray imaging, CT scans, continuous CT (CCT), magnetic resonance imaging (MRI), fluoroscopy, single photon emission CT (SPECT), positron emission tomography (PET), and the like. The imaging equipment allows an interventionalist, such as a radiologist, surgeon, physician, or other medical personnel, to track the insertion of interventional devices, such as biopsy needles, in a subject during diagnostic and therapeutic procedures. While such imaging modalities allow procedures to be performed with minimal invasiveness and are helpful to the interventionalist and the patient, they have certain drawbacks.
For example, with some image-guided procedures, e.g., those using CT imaging, the tracking of the needle position is not done in real-time. That is to say, a static image is obtained and the needle position noted therein. Subsequently, the needle is advanced or retracted by a small amount and another static image obtained to verify the new needle position. This sequence is repeated as many times as necessary to track the needle""s progression. Such a procedure tends to be time consuming insomuch as the needle progresses by only a short distance or increment between imaging, and needle progression is halted during imaging. Moreover, accuracy suffers to the extent that in the interim, i.e., between images, the needle""s position cannot be visualized.
With the development of CCT imaging and fluoroscopy, real-time imaging has been made possible. In CCT scanning, a rotating x-ray source irradiates the subject continuously, generating images at a rate of approximately six frames per second. The use of CCT or fluoroscopy by the interventionalist for real-time guidance and/or tracking of the needle during biopsies is gaining popularity. As a result, biopsies have become not only more accurate, but also shorter in duration. However, because of the imaging proceeds continuously, the patient and potentially the interventionalist are both exposed to a greater dose of radiation as compared to, e.g., non-continuous CT.
Accordingly, there exists in the prior art a trade-off between the level of radiation exposure experienced and real-time visualization of the procedure. That is to say, lower radiation exposure is conventionally achieved at the cost of real-time visualization, and conversely, real-time visualization is conventionally achieved at the cost of higher radiation exposure.
One problem resides in protecting the interventionalist from radiation exposure. In needle biopsies, for example, often the biopsy needle and guide are held within or close to the plane of the x-ray radiation so that the needle-tip will reside in the image plane thereby permitting continuous tracking. Staying close to the plane of imaging also, more often than not, allows for the distance the needle passes through the subject to be minimized. Consequently, this typically results in the interventionalist placing his/her hands in the x-ray beam. The hands of an interventionalist who performs several such procedures per day can easily receive a toxic dose of radiation. Therefore, it is desirable to provide interventionalists with a way to perform needle biopsies without the risk of radiation exposure.
A proposed approach to solving the aforementioned problem involves the use of a mechanical system which allows the interventionalist to manipulate the biopsy needle while his hands remain clear of the x-ray beam. However, such systems with mechanical linkages reduce or eliminate the tactile sensations (e.g., force, shear, and/or moment on the needle) otherwise available to an interventionalist directly manipulating the needle. This is disadvantageous in that interventionalists typically obtain useful information regarding the procedure from these tactile sensations. For example, they are often able to feel the needle transition between different tissue types, contact with bones, skin punch through, etc. The interventionalist generally desire this xe2x80x9cfeelxe2x80x9d as they perform biopsies. To trained personnel, it serves as an additional indication of the needle""s location.
Commonly owned U.S. Pat. No. 6,245,028 to Furst, et al., incorporated by reference herein in its entirety, addresses the lack of feel and interventionalist radiation exposure issues in part. However, insomuch as it employs a continuous imaging modality (e.g., CCT) radiation exposure to the patient may be higher than desirable.
The present invention contemplates a new and improved tactile feedback and display in an image guided robotic system for interventional procedures which overcomes the above-referenced problems and others.
In accordance with one aspect of the present invention, a system for conducting an image-guided medical procedure on a subject is provided. The system includes a medical imaging apparatus which intermittently during the procedure obtains, upon demand, real-time medical images of the actual procedure. A robotic arm holds a medical instrument that is used to perform the procedure. The robotic arm manipulates the medical instrument in response to drive signals from a haptic control. A detector measures forces experienced by the medical instrument during the procedure. The haptic control generates the drive signals in response to manipulations of an input device by an operator, and the operator receives tactile feedback from the haptic control in accordance with the measured forces experienced by the medical instrument. A display shows a virtual planning view of the procedure. The virtual planning view depicts a pre-procedure image of the subject with a virtual medical instrument corresponding to the medical instrument held by the robotic arm superimposed therein. In response to the drive signals from the haptic control, the virtual medical instrument has its position and orientation updated relative to the pre-procedure image.
In accordance with another aspect of the present invention, a method of conducting a medical procedure on a subject includes planning the medical procedure by obtaining a pre-procedure image of the subject and superimposing therein a virtual medical instrument that corresponds to an actual medical instrument used to conduct the medical procedure. A robotic arm holding the actual medical instrument is remotely controlled to conduct the medical procedure, and forces experienced by the actual needle are measured as the medical procedure is being conducted. The method also includes providing tactile feedback to an operator conducting the procedure based on the measured forces, and updating a position and orientation of the virtual medical instrument in the pre-procedure image in accordance with the controlling of the robotic arm. Additionally, real-time images of the actual medical procedure are obtained intermittently during the medical procedure.
In accordance with another aspect of the present invention, an apparatus is provided for performing a medical procedure on a subject with a medical instrument. The apparatus includes: imaging means for intermittently during the procedure obtaining, upon demand, real-time medical images of the actual procedure; robotic means for holding the medical instrument used to perform the procedure, the robotic means manipulating the medical instrument in response to a first signal; force detecting means for measuring forces experienced by the medical instrument during the procedure; control means for generating the first signal in response to manipulations of an input device by an operator and for providing the operator tactile feedback in accordance with the measured forces experienced by the medical instrument; and, display means for showing a virtual planning view of the procedure, the virtual planning view depicting a pre-procedure image of the subject with a virtual medical instrument corresponding to the medical instrument held by the robotic means superimposed therein, the virtual medical instrument, in response to the first signal from the control means, having its position and orientation updated relative to the pre-procedure image.
One advantage of the present invention is that it guards against excessive radiation expose to both the interventionalist and the patient.
Another advantage of the present invention is that it provides tactile feedback to the operator.
Yet another advantage of the present invention is that it permits the interventionalist to continually monitor and/or visualize the progression of the procedure via a virtual view of the same while intermittently obtaining real-time images of the actual procedure for verification.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.